1. Field of the Invention
The present disclosure relates to a liquid crystal display device and a method for manufacturing the same.
2. Discussion of the Related Art
A liquid crystal display (LCD) device, which is one of flat display devices recently drawing attention, is a device for applying an electric field to liquid crystals having both fluidity of liquid and an optical property of crystal to change optical anisotropy. Since the LCD device has low power consumption and a small volume, and can be made to have high definition in a large size, it is widely used.
Up to now, researches on an LCD device allowing a wider viewing angle is under active development, but recently, researches have also started working on an LCD device having a narrow viewing angle as well as a wide viewing angle is under active development.
For example, in the case where an LCD device is used for protecting company secret or the privacy of an individual, information may leak to or the privacy can be violated by a person positioned at an adjacent location when the LCD device has only a wide viewing angle.
For this reason, recently, technology for allowing an LCD device to be viewed in a desired viewing angle at a desired time by controlling the LCD device is under active development.
FIG. 1 is a cross-sectional view illustrating a related art LCD device that can operate in a wide viewing angle mode and a narrow viewing angle mode.
Referring to FIG. 1, the related art LCD device includes a first liquid crystal (LC) panel 11 and a second LC panel 12 attached to each other.
The first LC panel 11 includes a first substrate 10 and a second substrate 20 separated by a predetermined distance, facing, and attached to each other. A first LC layer 30 is interposed between the first substrate 10 and the second substrate 20.
Though not shown, thin film transistors (TFTs) and pixel electrodes can be formed on the inner surface of the first substrate 10, and color filters and a common electrode can be formed on the inner surface of the second substrate 20.
The second LC panel 12 is formed on the outer surface of the second substrate 20.
The second LC panel 12 includes a third substrate 50 and a fourth substrate 60 separated by a predetermined distance, facing, and attached to each other. A second LC layer 70 is interposed between the third substrate 50 and the fourth substrate 60.
Though not shown, a first electrode and a second electrode are formed on the inner surfaces of the third and fourth substrates 50 and 60, respectively. The first and second electrodes are connected to a predetermined controller to apply an electric field to the second LC layer 70.
The second LC layer 70 is aligned horizontally or vertically by the applied electric field.
A first polarizer 81 is formed on the outer surface of the first substrate 10 of the first LC panel 11, and a second polarizer 82 is formed on the outer surface of the fourth substrate 60 of the second LC panel 12.
At least one polarizer can be further provided between the first LC panel 11 and the second LC panel 12.
During a wide viewing angle mode, the second LC panel 12 directly passes an image generated by the first LC panel 11 regardless of application of an electric field to the second LC layer 70.
During a narrow viewing angle mode, a predetermined electric field is applied or not applied to the second LC panel 12 to pass light processed by the second LC panel 12 in only a predetermined direction. Therefore, an image that is generated by the first LC panel 11 and passes through the second LC panel 12 can be viewed at a specific narrow viewing angle.
As descried above, in the case where a viewing angle controlling LC panel is attached on a main LC panel providing a primary image to control the viewing angle of a related art LCD device, the viewing angle controlling LC panel not only should be additionally manufactured but also the thickness and weight of a product increase three times or more.
Also, misaligning can be generated while the viewing angle controlling LC panel and the main LC panel are attached to each other. Since light incident from a backlight unit should always pass through the viewing angle controlling LC panel during a wide viewing angle mode, front brightness considerably reduces.